CVE-2026-63344
Refitter: C# source injection through OpenAPI content-type map keys
Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.2, content-type keys in the content maps of requestBody/responses are emitted verbatim into a Refit [Headers("Accept: <ct>", "Content-Type: <ct>")] attribute string without escaping quotation marks. A crafted content-type key in an attacker-influenced OpenAPI description survives default validation without --skip-validation, breaks out of the attribute string and enclosing interface and namespace, and can introduce a top-level file class while leaving valid generated C#. A [ModuleInitializer] method in that class executes attacker code when the generated assembly is loaded at application startup, without requiring a call to the client. The behavior was verified with Refitter 2.0.0 and .NET 8. This issue is fixed in version 2.1.2.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Active
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
8.6
Refitter: C# source injection through OpenAPI content-type map keys
Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.2, content-type keys in the content maps of requestBody/responses are emitted verbatim into a Refit [Headers("Accept: <ct>", "Content-Type: <ct>")] attribute string without escaping quotation marks. A crafted content-type key in an attacker-influenced OpenAPI description survives default validation without --skip-validation, breaks out of the attribute string and enclosing interface and namespace, and can introduce a top-level file class while leaving valid generated C#. A [ModuleInitializer] method in that class executes attacker code when the generated assembly is loaded at application startup, without requiring a call to the client. The behavior was verified with Refitter 2.0.0 and .NET 8. This issue is fixed in version 2.1.2.
- Record
CVE-2026-63344- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Weakness
- CWE-94, CWE-116
- Updated
- 2026-11-06
EUVDEUVD-2026-114539
8.6
Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.2, content-type keys in the content maps of requestBody/responses are emitted verbatim into a Refit [Headers("Accept: <ct>", "Content-Type: <ct>")] attribute string without escaping quotation marks. A crafted content-type key in an attacker-influenced OpenAPI description survives default validation without --skip-validation, breaks out of the attribute string and enclosing interface and namespace, and can introduce a top-level file class while leaving valid generated C#. A [ModuleInitializer] method in that class executes attacker code when the generated assembly is loaded at application startup, without requiring a call to the client. The behavior was verified with Refitter 2.0.0 and .NET 8. This issue is fixed in version 2.1.2.
- Record
EUVD-2026-114539- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Updated
- 2026-11-06
NVD
8.6
Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.2, content-type keys in the content maps of requestBody/responses are emitted verbatim into a Refit [Headers("Accept: <ct>", "Content-Type: <ct>")] attribute string without escaping quotation marks. A crafted content-type key in an attacker-influenced OpenAPI description survives default validation without --skip-validation, breaks out of the attribute string and enclosing interface and namespace, and can introduce a top-level file class while leaving valid generated C#. A [ModuleInitializer] method in that class executes attacker code when the generated assembly is loaded at application startup, without requiring a call to the client. The behavior was verified with Refitter 2.0.0 and .NET 8. This issue is fixed in version 2.1.2.
- Record
CVE-2026-63344- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - Weakness
- CWE-94, CWE-116
- Updated
- 2026-11-06
OSV
8.6
Refitter: C# source injection through OpenAPI content-type map keys
Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.2, content-type keys in the content maps of requestBody/responses are emitted verbatim into a Refit [Headers("Accept: <ct>", "Content-Type: <ct>")] attribute string without escaping quotation marks. A crafted content-type key in an attacker-influenced OpenAPI description survives default validation without --skip-validation, breaks out of the attribute string and enclosing interface and namespace, and can introduce a top-level file class while leaving valid generated C#. A [ModuleInitializer] method in that class executes attacker code when the generated assembly is loaded at application startup, without requiring a call to the client. The behavior was verified with Refitter 2.0.0 and .NET 8. This issue is fixed in version 2.1.2.
- Record
CVE-2026-63344- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Weakness
- CWE-116, CWE-94
- Updated
- 2026-11-07
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| references | CVE List | |
| facts | NVD, OSV | |
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-63344 is a high vulnerability (CVSS 8.6) in Christianhelle Refitter, published October 30, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.35%, the 28th percentile. No source names a fixed version.
References
github.com/christianhelle/refitter/security/advisories/GHSA-p32v-8v8j-j534
github.com/christianhelle/refitter/pull/1178
github.com/christianhelle/refitter/commit/ab4d8e439d6f0ee82ad49ee15323978d70fe5a67
github.com/christianhelle/refitter/releases/tag/2.1.2
github.com/user-attachments/files/29394848/reproduce.sh
github.com/user-attachments/files/29394851/maintainer-report.txt
github.com/user-attachments/files/29394853/make_spec.py
github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63344.json
nvd.nist.gov/vuln/detail/CVE-2026-63344